the conversation changed -- turned into "don't worry about him." "don't worry about him helping with the baby." >> reporter: they thought that's all it was, derek didn't want to help raise his child. now they replayed that moment over and over. >> we should've said, "wait, what did he say -- what did he say to you?" but instead of that we were like, "we don't need him. like, just hang up. don't even talk to him." you know, that kind of just -- >> yeah, that's exactly what we said. >> showing her the kind of support. 'cause we're so used to just picking up our burdens and going. >> she brought on it up that she was worried, but you didn't hear it or it didn't sound bad enough. you're all kind of beating yourself up for not listening to crystie's warning. >> exactly. >> right. >> even though it sounds to me like you'd almost have to be a mind reader to know that she was really concerned. >> yeah. >> reporter: the years started to pass. and this family thought a lot about derek smyer. crystal had said if something happened to her, it was derek. they believed he was the only one who had something to gain from her death.